Affordance is an important aspect of any GUI, because the user must be able to figure out what can be done with the visible objects by applying the general conventions of GUI interaction. In the usual case of static objects, an object can be acted upon by pointing at the area where it is seen, and then touching or clicking inside the area.
A display based on dynamic distortion complicates this simple pointing procedure. With distortion together with magnification for example, the objects' display sizes depend on the changing pointer position. But the objects are also displaced in the direction opposite to the pointer movement. When pointing to where an object was previously seen, the user may find that the object is no longer there to be acted upon, because the object itself has moved, in this sense, distortion is defined as the decoupling of the control coordinates of an object from its display coordinates.
In Patent Cooperation Treaty application No. PCT/ZA2014/000013, the applicants described an invention in which they addressed the problem of difficult focus targeting that appears when navigating a distortion display, by introducing a focal dip into the magnification function and by controlling the object scaling separately from the magnification of the background space.
Distortion induced decoupling between control and display coordinates will disrupt interaction if the user relies purely on ballistic movements and muscle memory. Nevertheless, as long as the changing pointer position remains a fixed point of the distortion function, such as with fish eye magnification, visually guided interaction remains possible. Such interaction benefits from the visual magnification even though there may be no motor advantage.
Distortion displays are known n the art. The one with the widest public deployment may be the Apple Dock implementation of a fish-eye view effect on the icons of a userbar [1].
Transfer of information from display to control in the context of the Apple Dock has been implicitly proposed by Zhai et al [2]. Their method involves freezing the display for a second or so on entry of the pointer into the userbar. The frozen display coordinates are then interpreted as control coordinates during the freeze, after which those coordinates lapse tack to being dynamic, and are used again purely for display. This technique amounts to a once-off information transfer from display to control at the instant of pointer entry into the userbar.
Another application of the discrete transfer from display to control may be found in the Semantic Pointing technique of Blanch et al [3]. When the display boundaries of certain regions on the screen are crossed by the pointer, the C-D ratio of the input device is adapted in a single step. This has the effect of changing the size of those regions in motor space, making selection easier or more difficult, depending on the slope of the C-D function.
However, these methods are discrete, with sudden changes, and “movement” of the objects rely on computer animation instead of being controlled by the user.
It is an object of this invention to provide an improved method for human computer interaction, which exploits advantageously the decoupling of control and display in distortion scenarios.